1. Field of the Invention
The present invention relates to electrical power supplies, and more specifically to an improved power supply for an overcurrent trip system.
2. Description of the Prior Art
A power supply for an overcurrent circuit trip system, for instance of the type shown in U.S. Pat. No. 4,271,447, contains a device to receive and rectify line currents whereby current transformers coupled to the lines are connected to a full wave rectifier circuit. The DC output of the rectifier circuit is connected through a sensing resistor to the input side of a voltage regulator which provides a controlled reference voltage, the voltage regulator containing an adjustable potentiometer. Two charging capacitors are connected to the output of the voltage regulator to provide capacitive storage. A trip network of a known type is provided for outputting a trip signal for initiating the tripping action. Also connected to the output side of the voltage regulator is the series combination of a control switch and the coil of a release magnet as, for example, is disclosed by U.S. Pat. No. 4,274,121. To control the line current, a release circuit is connected to the adjusted output of a sensing resistance which, in turn, will trigger the release signal. A control switch is also connected to receive the release signal. Such power supply systems typically provide power for the operating trip network, as well as the energy for tripping the releasing magnet.
It will accordingly be understood that an object of the invention is to provide a power supply for an overcurrent circuit trip system which provides a low-loss supply for the release circuit, and guarantees that the release magnet will operate with the shortest possible reaction time.